1. Field of the Invention
The present invention relates to an ignition apparatus for an internal combustion engine mounted in, for example, an automobile, and more particularly to an ignition apparatus for an internal combustion engine in which a high voltage for ignition is generated in a secondary coil of an ignition coil by allowing and shutting off a flow of a current to a primary coil of the ignition coil by means of a switching element.
2. Description of the Related Art
A conventional ignition apparatus for an internal combustion engine is provided with resistors through which a current corresponding to an ion current and a current of an ignition signal are caused to flow, respectively, a comparator for comparing voltages generated in the resistors with each other, and a switch for making a switchover between the current of the ignition signal and the current corresponding to the ion current based on a result of the comparison, with a view to outputting an output from a circuit for detecting an ion current via the same route as is followed by the ignition signal (e.g., see JP 2004-156608 A).
However, this ignition apparatus is susceptible to an influence of a discrepancy in characteristics between the resistor configured on a coil side and the resistor for supplying the ignition signal and the influence of the potential of a ground GND, thereby causing problems in that the ignition signal cannot be supplied to a switching element with accuracy and that the size of the circuit is increased.